I saw an alternative spelling of the name Grayson that I kind of liked that looked a little bit more feminine (at least to me) and I typically don't like unusual name spellings. I think Gracyn and Emerson are cute together especially with the nn you were talking about using (Emme and Gracie is so cute!) I also think the name Avery goes very well with the name Emerson.

I'm not crazy about Grayson with Emerson, just because the two -son endings seem a bit matchy to me. Have you considered just Gray on its own? Although I agree that Rosalind is lovely, I also think a unisex name would work better with Emerson. How about: